Why would sand be deposited behind a small island to form a spit or tombolo?

Sand is deposited behind a small island to form a spit or tombolo due to the combined effects of wave action and longshore currents. As waves approach the island, they lose energy and deposit sediment on the leeward side, creating a sandbar that extends toward the mainland. Over time, this accumulation of sand can connect the island to the shore, forming a spit or tombolo. The process is influenced by factors such as prevailing winds, tidal patterns, and the shape of the coastline.